Symbolic Link Case Sensitivity Exploit Bypasses System Security

ID: Q222159

The information in this article applies to:
  • Microsoft Windows NT Server versions 4.0, 4.0 SP1, 4.0 SP2, 4.0 SP3, 4.0 SP4
  • Microsoft Windows NT Workstation versions 4.0, 4.0 SP1, 4.0 SP2, 4.0 SP3, 4.0 SP4
  • Microsoft Windows NT Server, Enterprise Edition versions 4.0, 4.0 SP4

SYMPTOMS

When you modify the "\??" object folder's symbolic link table by substituting a different case (upper versus lower) letter in the table to point to a different device associated with a disk drive alias, it may be possible to bypass typical Windows NT security and allow any user to acquire administrator privileges.


RESOLUTION

To resolve this problem, obtain the latest service pack for Windows NT 4.0 or the individual software update. For information on obtaining the latest service pack, please go to:

For information on obtaining the individual software update, contact Microsoft Product Support Services. For a complete list of Microsoft Product Support Services phone numbers and information on support costs, please go to the following address on the World Wide Web:
http://www.microsoft.com/support/supportnet/overview/overview.asp



Once you have installed the Windows NT 4.0 service pack, it is necessary to enable base system object restrictions to prevent the use of this security exploit. To do this:
  1. Click Start, click Run, type regedt32, and then click OK.


  2. On the Windows menu, click HKEY_LOCAL_ MACHINE on Local Machine.


  3. Double-click the \System\CurrentControlSet\Control\Session Manager folder.


  4. Double-click the ProtectionMode value, type 1, and then click OK.


  5. Quit Registry Editor, and then restart the computer.



STATUS

Microsoft has confirmed this to be a problem in the Microsoft products listed at the beginning of this article. This problem was first corrected in Windows NT 4.0 Service Pack 5.

Additional query words:

Keywords : nt4sp5fix
Version : winnt:4.0,4.0 SP1,4.0 SP2,4.0 SP3,4.0 SP4
Platform : winnt
Issue type : kbbug


Last Reviewed: November 1, 1999
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